Brake mechanism for lifting-jacks.



I. E. HZNMAN.

BRAKE WICHANIS FOR LIFTMG lACKS.

APPLICATION mm MAR. 2. um

SP6 k WITNESSES INVENTOR a fhg y (mfl mum (MAM E( @xiii (Q /MCM l@ Q 2xQ Patented my um.

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][STL' E. HINDMAN, OF GRAFTON, PENNSYLVANIA, ASSG-NOE, TO THE JDUFFMANU- FACTUMING- COMPANY, OlE PITTSBURGH, PENNSYLVANIA, A CORPORATION OFIPENNSYLVANLVM.

To all whom t mail concern,

Be it lmown that l, daarin E. lli-noemer, a citizen of the `UnitedStates, residing at Grafton, in the county of Allegheny and State ofPennsylvania, have invented a new and useful llinprovement in BrakeMechanisin for Lifting-Jacks, of which the followin is a full, clear,and enact description., reierence being had to the accompanying drawins, :torming part oi this specification, in whic t lligure 1 is asectional view, partly broken away, oi a lifting jack embodying inyinvention.

hig. 2 is a detail view, partly in end elevation and partly in verticalsection showing the manually controlled brake device.

My invention has relation to brake mechanism for load raising andlowering apparatus, and is more particularly applicable-to lifting jackset the class known as high speed screw jacks. rihe invention is furtherparticularly applicable to that type of high speed screw jack known asthe self rundown jacks, in which. the angle of the thread of the mainlifting screw is Sadi-- cientl great to permit the load to torce thejack own after it has been raised.

My invention is designed to provide a brake mechanism ier a jack oi thischaracter by means oi." which both the speed and the extent of thelowering may be perfectly controlled without jarring or injury to thejack, its load, or its support, under manimum loads.

l accomplish this object by the provision of an auxiliary train of gearswhich is 'idle during the raising movement of the jack and which isarranged to be brought into action during the lowering movement; andalso by the provision and connection with the auxiliary gears oiI a loadoperated automatic brake device. li also preferably provide inconnection therewith a manually operated brake deviceg ldy inventionwill be best understood by reference to the accompanying drawing, inwhich l have shown the preferred embodiment thereof* and which will nowbe described, it being premised, however, that various changes can bemade in the details oit construction and arrangement of the s everalparts, without departing from the spirit specification of LetteraEatent.

:HEME 'MECHNSM FOR LIFTIil'G-JACKS.' v

Patented duly 2d, ildilt.

Application flied March 2, 191th aerial 1t' o; 152,021.

and scope of my invention, as dened in the appended claims.

lin the drawings, the numeral 2 designates a suitable basesupporting'the standard 3, and fl designates the housing of the jackprovided with a sleeve portion 5, which has a sliding it with thestandard 6 is the top or load sup orting plate carried by the housing4l, and is the main lifting screw. 'lhis screw may be actuated by anysuitable or usual mechanism to raise the load. in the drawing l haveindicated a beveled pinion 8 carried by a shaft 9, which may be actuatedin any usual or 'suitable manner, the pinion meshing with the beveledgear wheel 10 rigidly fixed to the upper portion of the screw 7.

11 designates a spur gear wheel which is also xed to the upper portionof the screw 7 above the gear wheel 10 and which meshes with the spurpinion 12 on a vertical shaft 13. This shaft 13 has a singleactingclutch la by which it is connectedto a beveled gear wheel 15meshing with another beveled gear wheel 16 which drives a train ofmultiplying gears 1'?. rlhe last wheel 17a of this train is a wormwheel, and has its teeth in mesh with a worin 18 on a transverse brakeshaft 19 journaled'in the housing 4.

20 is a brake disk which is slidably mounted on the shaft-,19 formovement toward and away from the iXed abutment 21 (which may be formedas a part ot the housing fi). rThis brake disk and the adjacent face ofthe abutment 21 are provided with suitable cooperating lfrictionsurfaces. Connected to the sleeve or hub portion 22 of the brake diskare jointed links 23 which carry the governor balls 24:, the links beingconnected at their opposite ends to the collar 25 fixed to the shaft 19.

26 is a brake wheel which is also fixed to the shaft 19 and which isengaged by pivoted jaws 27, which are pressed against the wheel 26 bythe action of a spring 28. These jaws may be separated to release theirbraking action by any suitable manually actuated device, such as thecrank shaft 29 carrying the spreadingcam 30 between said jaws.

When the jack is being raised, the spur gears 11 and 12 are revolved,but the action of the clutch 14: is such as to leave the beveled gearand the train ot multiplying gearing idle. rfhe brake jaws 27 arepressing against the brake wheel 26, but as the clutch 14 is notoperatively engaged, t h1s braking action does not retard the raising ofthe jack. As soon, however, as the raising effort is released, thereverse action of the main screw 7 and of the gears 10, 11 and 12causes'the clutch 14 to become operatively engaged, thereby tending torevolve the auxiliary gears and the shaft 19. The brake jaws 27 are nowfully operative and hold the load by preventing reverse movement of thescrew 7. When self-lowering is required, the crank 29 is operated in adirection to release the brake jaws 27. The shaft now commences torevolve and as the speed increases the governor balls 2 4 fly outwardly,ythereby bringing the friction disk 20 into braking engagement with theabutment 21. 1n this manner, the speed of self-lowering may beautomatically controlled so as not to become excessive, and the load canbe stopped at any desired point at any time by again turning the crank29 to permit the brake jaws 27 to again engage the brake wheel 26.

The advantages of'my invention will be readily understood since itprovides a selflowering high speed screw jack which can be either heldagainst lowering movement scribed, since it will be obvious that there.

are many devices of this character known in the arts which may besubstituted for the particular forms thereof which 1 have herein shownand'r described. It will also be understood that the train of auxiliarygearing may be arranged `otherwise than as shown herein and that variousstruction and arrangement of the parts within the spirit and scope ofthe appended claims.

My invention may also be applied to other forms of load liftingapparatus.

l claim:

1. A load lifting apparatus having a main lifting screw with means foractuating the same, a train of auxiliary gearing, .a

single actingclutch connection between the' screw and the auxiliarygearing and arranged to operate the auxiliary gearing only when thescrew is turning in a loadothery changes may be made in the details of.conlowering direction, and a brake shaft driven by said gearing,together with an automatic speed controlled braking device operated bysaid shaft and auxiliary gearing; substantially as described.

2. A load 'lifting apparatus having a main lifting screw with means foractuating the same, a train of auxiliary gearing, a single acting clutchconnection between the screw and the auxiliary gearing and arranged tooperate the auxiliary gearing only when the screw is turning in aload-lowering direction, a brake shaft driven by said gearing, a brakingmember carried by said shaft, coperating braking means normallyengigingsaid member, and means for manna y releasing the cooperatingbraking means; substantially as described.

3. A load lifting apparatus having a main lifting screw with means foractuating the same, a train of auxiliary gearing, a single acting clutchconnection between the screw and the auxiliary gearing and arranged tooperate the auxiliary gearing only when the screw is turning in aload-lowering direction, a brake shaft driven by said caring, and anautomatic'speed controlled raking device operated by said shaft andauxiliary gearing, said shaft also having a manually controlled brakingdevice; substantially as described.

4. In a quick action self-lowering jack, the combination with a mainscrew, of an auxiliary train of gearing, a driving connection betweenthe main screw and the train of gearing, said connection including asingle acting clutch which is arranged to actuate said gearing only whenthe screw is turning in a load-lowering direction, a brake shaft havingaworm gear connection with said auxiliary train, and an automatic speedcontrolled brake device actuated by said shaft; substantially asdescribed.

5. In a quick action self-lowering jack, the combination with a mainscrew, of an auxiliary train of gearing, a driving connection betweenthe main screw and the train of gearing, said connection including asingle acting clutch which is arranged to actuate said gearing only whenthe screw `is turning in a load-lowering direction, a

brake shaft having a worm gear connection with said auxiliary train, andan automatic speed controlled brake device actuated by said shaft, saidshaft also having a manually controlled brake device; substantially asdescribed.

6. 1n a quick action self-lowering jack, the combination with a main,load-lifting screw, of a train of auxiliary gearing having drivingconnection with said screw, said driving connection including a singleacting clutch, and an automatic brake device actuated by said train ofgearing; substantially as described.

7.111 a quick action self-lowering jack, with a hand controlled brakedevice also the combination With a main load-lifting arranged to actupon the screw through said screw, of a train of auxiliary gearinghavgearing; substantially as described. 10 ing driving connection Withsaid screw, said In testimony whereof I have hereunto set drivingconnection including a single acting my hand. clutch, and an automaticbrake device actuated by said train vof gearing, together ISAIAH E.HINDMAN.

